diff --git a/views/index.html b/views/index.html
index 2a0833e..16216fc 100644
--- a/views/index.html
+++ b/views/index.html
@@ -364,7 +364,7 @@
             <div class="fn-right">
                 <img class="gravatar"
                      onerror="this.src='/static/images/user-thumbnail.png'"
-                     src="https://secure.gravatar.com/avatar/{{.user.Gravatar}}?s=17&d=http://symphony.b3log.org/images/user-thumbnail.png" 
+                     src="https://secure.gravatar.com/avatar/{{.user.Gravatar}}?s=17&d=https://symphony.b3log.org/images/user-thumbnail.png" 
                      title="{{.user.Name}}"/>
                 <span class="font-ico ico-share"></span> &nbsp;
                 <span onclick="window.open('https://github.com/b3log/wide')"
diff --git a/views/preference.html b/views/preference.html
index b6482f5..9cdb3b4 100644
--- a/views/preference.html
+++ b/views/preference.html
@@ -92,7 +92,7 @@
             </label>
             <label class="fn-clear">
                 <img onerror="this.src='/static/images/user-thumbnail.png'"
-                     src="https://secure.gravatar.com/avatar/{{.user.Gravatar}}?s=48&d=http://symphony.b3log.org/images/user-thumbnail.png" 
+                     src="https://secure.gravatar.com/avatar/{{.user.Gravatar}}?s=48&d=https://symphony.b3log.org/images/user-thumbnail.png" 
                      title="{{.user.Name}}" class='gravatar'/>
                 <a href="http://gravatar.com/" target="_blank">{{.i18n.change_avatar}} Gravatar.com</a>
             </label>